RU103935U1 - EARTH REMOTE SENSING DEVICE USING THE MULTI-POSITION RADAR SYSTEM - Google Patents

Abstract

 A device for remote sensing of the Earth using multi-position radar systems, containing a transmitting position, including transmitters of orthogonal sounding signals, and a receiving position, located on board an airborne aircraft (VLA), containing a weakly directional antenna and an antenna system that forms M independent non-overlapping radiation patterns directivity of a weakly directed antenna and antenna system are oriented towards transmitters of the transmitting position and of the earth’s surface, respectively, the antenna system is connected respectively to the receivers of the reflected navigation signals, the outputs connected to the formers of the sequence of power values of the indicated signals, the outputs connected to the formers of the complete radio images, the outputs connected to the first input of the visualization of the current radio images, with the second, third and fourth inputs of which are connected output of the on-board storage device for a digital terrain map, on-board flight altitude sensor, pitch and roll of VLA, and consumer navigation equipment, to the input of which a weakly directional antenna is connected, the outputs of the visualization devices for the current radio images are connected to the inputs of the radio communication equipment.

Description

The utility model relates to the field of radar and can be used in remote sensing systems of the Earth from mobile carriers.

A known method and device for remote sensing of the Earth using an aviation multi-position radar system with a synthesized aperture (MP SAR) (see Radar stations for Earth survey / edited by G.S. Kondratenkov. - M .: Radio and communications, 1983, 272., page), using one transceiver and two receiving positions. Such MEA SARs are used in practice, however, they do not have the speed of shooting, since in order to obtain an image of a site, it is necessary, firstly, to record the radio hologram of the reflected signal, secondly, to deliver its processing point and, thirdly, to synthesize the radio image. Therefore, such MP SARs are not used for an operational survey of the Earth's surface.

The closest in essence to the claimed utility model (prototype) should be considered the device for remote sensing of the Earth described in patent No. 2278398 with priority dated July 6, 2004 (authors Sakhno I.V., Fateev V.F.). The device includes N transmitters and one receiving position and performs the following operations:

1. N independent orthogonal signals S ₁ .... S _N are emitted from the board of N transmitting positions (Rx).

2. Oriented radiation patterns (NAM) of all N transmitting positions on a given plot of the earth's surface.

3. The radiation pattern of the first receiving antenna is directed toward a given portion of the earth’s surface, and the beam patterns of the second weakly directed receiving antenna are oriented in the direction of N transmitting positions.

4. On board the receiving position using the antenna, oriented in the direction of a given section of the earth's surface, N orthogonal signals are received reflected from the observed portion of the earth's surface.

5. On board the receiving position, with the help of an antenna oriented towards the transmitting positions, N direct orthogonal signals of direct propagation S _1PR ... S _NPR are received directly from the N transmitting positions.

6. From propagation signals allocate information about the status of each transmitter and its carrier, as well as the state of the propagation medium.

7. On board the receiving position for each pair of N direct and reflected signals corresponding to each other, N radar holograms are recorded corresponding to N different angles of irradiation of the observed portion of the earth's surface by each of the transmitter carriers.

8. On board the receiving position, N different angular radar images (RLI) of the observed area of the earth’s surface are simultaneously synthesized.

9. Perform a joint analysis of a set of N different radar images.

This device has a low efficiency of receiving radio images of the area, since operations 7 (recording holograms), 8 (synthesis of radio images) and 9 (analysis of radio images) require considerable time. With the current level of development of on-board computers using signals from the GLONASS and GPS space navigation systems, the delay in receiving radio images reaches tens of minutes, and the entire processing device is very complex and has large dimensions, weight and power consumption. For this reason, the use of the device in question for the operational monitoring of land from aboard small-sized unmanned aerial vehicles (UAVs) is difficult due to the large size and power consumption of the device and inefficient due to the inability to observe the Earth in real time.

The technical result of the utility model is to increase the efficiency of obtaining radio images of the underlying surface of the Earth and simplify the device.

The Earth remote sensing device comprises a transmitting position, including transmitters of orthogonal sounding signals, and a receiving position, located on board the aircraft, containing a weakly directional antenna and an antenna system that forms M independent non-overlapping radiation patterns. The directional patterns of a weakly directed antenna and antenna system are oriented towards the transmitters of the transmitting position and the earth's surface, respectively. The antenna system is connected respectively to the receivers of the reflected navigation signals, the outputs connected to the formers of the sequence of power values of the indicated signals, the outputs connected to the formers of the complete radio images, the outputs connected to the first input of the visualization of the current radio images, with the second, third and fourth inputs of which the output of the onboard storage device is connected digital terrain map, on-board flight altitude sensor, pitch and roll of VLA, and navigation consumer equipment, to the input of which a weakly directional antenna is connected, the outputs of the visualization device for the current radio images are connected to the input of the radio communication means.

The list of operations that the device performs differs from the prototype and consists in the following:

1. From the board of N transmitting positions, transmitters (Rx) emit N independent navigation orthogonal sounding signals S ₁ .... S _N.

2. Oriented radiation patterns (NAM) of all N transmitting positions on a given plot of the earth's surface.

3. In the weakly directed antenna of each receiving position, one or more beams of the radiation pattern are formed and directed towards the transmitting positions.

4. In the antenna system of the receiving positions, M independent non-overlapping rays of the radiation pattern are formed and directed towards the observed portion of the earth's surface.

5. On board the receiving position using the rays oriented to the transmitting position, receive N orthogonal sounding signals of direct propagation directly from N transmitting positions.

6. Of the orthogonal sounding signals of direct propagation allocate information about the status of each transmitter and its carrier, as well as the distribution environment.

7. Navigation orthogonal sounding signals of N transmitting positions reflected from sections of the earth's surface receive at a receiving position on M independent receiving beams on M independent receivers (one for each beam).

8. In each receiver, the arrival time of the reflected orthogonal sounding signals is measured. from a sequence of m elementary sections of the earth’s surface “covered” by the corresponding receiving beam.

9. At the output of each receiver, a sequence of values of the power of the reflected signals S _{neg1-N of} all N transmitting positions for each m-th elementary section is formed, and these powers are summed up taking into account information about the state of each transmitter, its carrier and the propagation medium.

11. Form the envelope of the radio brightness of elementary sections of the earth's surface. To do this, the results of summing the power of the received reflected signals are arranged on the time axis according to the time of arrival of the reflected signals: from the earliest to the latest.

12. The envelope of the radio brightness is fed to the time-sweep system of the visualization device, an analysis of the results of radar observation of a plot of the earth's surface is carried out, highlighting the brightest point and determining the coordinates of the target (object) by combining the radio image with a digital map of the area.

A device for remote sensing of the Earth using a multi-position radar system (radar) based on signals from satellite navigation systems GLONASS, GPS, GALILEO, is illustrated by drawings.

Figure 1 presents a diagram of a device for obtaining a radar image of the earth's surface using a multi-position radar

Figure 2 shows the location of the beam relative to the earth's surface and the receiving position

Figure 3 shows the power diagrams of signals reflected from elementary sections of the earth's surface

Figure 4 shows a radio image of a plot of the earth's surface

Figure 5 shows a diagram for determining the boundaries of the trail of the pathway. In the drawings, the following notation:

1 - transmitting positions in the form of navigation spacecraft (NSC) of the GLONASS, GPS, GALILEO satellite navigation systems, with transmitters emitting orthogonal navigation sounding signals S ₁ , S ₂ ..S _N , where N is the number of spacecraft simultaneously visible at a given point on the earth surface;

2 - board an airborne aircraft (VLA) - receiving position;

3, 4 - sections of the earth's surface irradiated by navigation orthogonal sounding signals S ₁ ... S _N ;

5 - weakly directional antenna for receiving direct propagation signals (reference signals) S _1PR ... S _NPR directly from the _satellite ;

6, 7 - VLA antenna system, for example, in the form of side-view antennas, for receiving signals S _1otr ... S _{Notr to the} left and right of the fuselage reflected from the reflection elements;

8, 9 - non-overlapping beams of the directional antennas of the side view 6 and 7, directed to both sides of the fuselage in sections 4 and 3, respectively;

10 - consumer navigation equipment (NAP) of GLONASS, GPS, GALILEO systems, determining the coordinates, speed and course of VLA;

11 - on-board sensor for flight altitude, pitch and roll of VLA;

12 - on-board storage device for digital terrain maps (CCM), over which the VLA moves;

13 ₁ , 13 ₂ - receivers of reflected navigation signals S _1otr ... S _Notr connected to the side-view antennas 6 and 7, respectively;

14 ₁ , 14 ₂ - shaper of the sequence of power values of signals reflected from elementary participants m of the earth's surface (shapers of elementary strings of radio images);

15 ₁ , 15 ₂ - shapers of complete radio images corresponding to both antennas of the side view;

16 ₁ , 16 ₂ - device for visualization of current radio images;

17 - radio communication means for the operational transmission of the current radio image to the receiving point;

18 - radio antenna;

19 is an on-board timeline storage device.

The device includes transmitting positions 1 and receiving position 2, which is located on board an aircraft. Transmitting positions include transmitters of orthogonal sounding signals. As the transmitting positions, navigation satellites (NSC) 1 ₁ , 1 ₂ , 1 _N of the GLONASS, GPS, GALILEO satellite navigation systems, which travel in orbits about 20 thousand kilometers above the Earth, are used. The transmitters radiate probing signals toward the earth's surface in the form of broadband noise-like signals in the ranges f ₁ = 1.5 GHz and f ₂ = 1.2 GHz. In the formation of radio images on board an airborne aircraft (VLA) 2, all visible spacecraft are involved, the number of which for VLA is 6-12 pieces simultaneously for each of the systems (GLONASS, GPS, GALILEO).

Both manned and unmanned aerial vehicles (UAVs) (aircraft, helicopter, cruise missile, balloon, etc.) can be used as a VLA carrier for receiving equipment.

The device operates as follows:

1. From the board of the transmitting positions (1), which are used as GLAASS, GPS, GALILEO systems, the transmitters in the direction of the Earth emit N navigation orthogonal sounding signals S ₁ ... S _N in two frequency band f ₁ and f ₂ that irradiate sections Earth's surface 3 and 4.

2. The directivity patterns (LH) of the VLA 6 and 7 side-view antennas are oriented toward the Earth’s surface to the left and right of the fuselage of the VLA 2 (back view of FIG. 2), and the directivity pattern of the weakly directed antenna 5 is oriented in the direction of the upper hemisphere of space toward N visible NKA. In this case, the antenna bottom 5 covers the upper hemisphere of space (α = 170 ÷ 180 °), and the non-overlapping rays 8 and 9 of the bottom antenna 6 and 7 “cover” surface areas 3 and 4, respectively. For these rays, the reflected signals S _1otr ... S _Notr ( _Fig.1 , Fig.2) through the antennas 6 and 7 are sent to the input of the receivers of the reflected signals 13 ₁ and 13 _2, respectively, where they are separated by the numbers of the irradiating satellites.

3. On board the receiving position 2 using the antenna 5, oriented in the upper hemisphere of space and connected to it NAL 10 receive N orthogonal sounding signals of direct propagation S _1pr ... S _Npr from the transmitting positions 1 ₁ -1 _N.

4. Ephemeris information about all visible spacecraft is extracted from direct propagation signals in NAP 10, the on-board storage device of the time scale 19 is synchronized by the time signal of the spacecraft, and the current coordinates X, Y of the projection of the VLA on the Earth's surface, the speed and course of the VLA are determined.

5. Using the sensor 11 determine the current height H VLA, as well as the pitch angle and roll angle β, which affect the position of the rays 8 and 9 of the bottom side antennas 6 and 7 (figure 2). Using these parameters, determine the sizes of the “covered” by the rays 8 and 9 sections of the earth’s surface 3 and 4. The sizes of the sections 3 and 4 are equal if the width of the rays 8 and 9 is the same, and β = 0.

6. In the visualization device of the current radio images 16 ₁ and 16 _{2, the} coordinates of the middle of the digital terrain map (CCA) from the on-board storage device 12 are coordinated with the coordinates of the VLA 2 X, Y coming from NAP 10, and the directions of the axes of the CCM are coordinated with the VLA course coming from sensor 11.

7. In the shapers 14 ₁ and 14 ₂ form a sequence of values of the power of the signals reflected from elementary sections of the earth's surface.

The essence of this operation is illustrated by the example of the right side-view antenna 9, the beam of which covers a plot of terrain 3 (Fig. 3). The minimum resolved length δ _{m of an} elementary portion of the earth’s surface m is determined by the duration of the elementary signal τ _{0 of the} pseudo-random sequence generating the signals S ₁ -S _{N of the} satellite: δ _m = τ ₀ s, where C is the speed of light.

The signals from the transmitters NKA S ₁ , S ₂ ..S _{N are} simultaneously reflected from the elementary portion of the earth's surface m. The power of the signals reflected from this section is , . From the output of the receiver 13 ₂ these signals are removed separately and fed to the shaper 14 ₂ . In the shaper 14 ₂ these powers are summed up and get the sum of powers for one elementary section m

For all elementary sections along the trace of the radiation pattern 1z, a sequence of values of the total power (Fig. 3) is formed as a function of the current length 1 _{3 of the} DN trail:

which represents the elementary row of the radio image for time t _j . This line is recorded in the memory of the shaper 14 ₂ .

In the shaper 14 ₁ similarly form and record the line of the left radio image (for a plot of terrain 4) as a function of the current length 14 ₄ traces of the daylight:

8. In the shapers 15 ₁ and 15 ₂ form and record the radio images R ₃ , R ₄ of the terrain as a function of the total power of the reflected signals from the distance along the track of the antenna pattern 1 ₃ , 1 ₄ and time t (figure 4):

;

9. In the devices 16 ₁ , 16 ₂ carry out the visualization of radio images and combine them with a digital map of the area from the on-board storage device CCM 12.

The combination with the CCM is made at the points: along the X, Y coordinates of the VLA and the coordinates of the boundaries of the DN 9 trace on the plot of the earth's surface 3: and figure 5).

The coordinates of the boundaries of the trace are determined from the formulas:

;

,

where γ ₁ and γ ₂ are the angles of inclination of the boundaries of the DN to the vertical,

H - VLA flight altitude.

In the presence of a roll β, the coordinates of the boundaries of the MD are determined from the formulas

;

.

After combining the MSC and the received radio images, they are analyzed and the coordinates of the targets on the earth's surface are determined by their coordinates on the combined MSC

10. Using the radio communication means 17 and the radio communication antenna 18, the current radio images, if necessary, are transmitted to the receiving point.

11. Using the on-board storage device, the time scales 19 synchronize all radio imaging devices. The device has the following advantages.

1. The device is much simpler than the prototype device, since it does not contain a device for recording holograms and synthesizing radio images. The weight of the proposed device and its power consumption are several times less.

2. The device provides a higher efficiency of receiving radio images, characterized by a delay in their receipt per unit time. In the prototype, due to the need for synthesis, the delay reaches tens of minutes.

3. Let us evaluate the resolution along and across the path.

The resolution along the path is determined by the ratio

where λ is the wavelength of radio waves;

D _PRM - the length of the aperture of the antenna, which forms the width of the side beam;

R is the distance to the target.

At λ = 0.2 m (f = 1.5 GHz),

D _prm = 2 m, R = 500 m, we have δx = 50 m.

As the altitude decreases, the resolution increases.

The resolution across the path is determined, as noted, by the duration of the elementary signal of the pseudo-random M-sequence forming the navigation signal: δ ₁ = τ ₀ s. For the δ Glonass system, τ ₀ = 0.2 μs. For GPS, τ ₀ = 0.1 μs.

Accordingly, δ _1glon = 60 m, δ _1GPS = 30 m.

These characteristics are not worse than the prototype.

The device allows you to get images of targets disguised in the technology of "stele". This is due to irradiation of targets with satellite signals from almost different sides in the multi-position radar mode.

The device provides radar immunity to passive interference such as corner reflectors, which is effective only in monolocation.

6 The method and device allow a significant increase in the signal-to-noise ratio when receiving satellite signals reflected from the ground. When using NAL, simultaneously receiving signals from GLONASS GPS, GALILEO systems in two frequency ranges f ₁ = 1.5 GHz and f ₂ = 1.2 GHz and with an average number of visible NS of each system of 10 pieces, we obtain a signal-to-noise ratio increase to 60 (10 × 3 × 2). The proposed method is advisable to use on board small-sized aircraft such as micro-aircraft, unmanned aerial vehicles, airships, balloons.

Claims (1)

A device for remote sensing of the Earth using multi-position radar systems, containing a transmitting position, including transmitters of orthogonal sounding signals, and a receiving position, located on board an airborne aircraft (VLA), containing a weakly directional antenna and an antenna system that forms M independent non-overlapping radiation patterns directivity of a weakly directed antenna and antenna system are oriented towards transmitters of the transmitting position and of the earth’s surface, respectively, the antenna system is connected respectively to the receivers of the reflected navigation signals, the outputs connected to the formers of the sequence of power values of the indicated signals, the outputs connected to the formers of the complete radio images, the outputs connected to the first input of the visualization of the current radio images, with the second, third and fourth inputs of which are connected output of the on-board storage device for a digital terrain map, on-board flight altitude sensor, pitch and roll of VLA, and consumer navigation equipment, to the input of which a weakly directional antenna is connected, the outputs of the imaging devices of the current radio images are connected to the inputs of the radio communication equipment.